wp_redirect()给出了混合内容错误

I recently moved my site over to https and everything is working, but a plugin that I am using to submit a form that is supposed to redirect on submit is not working.

It is using the wp_redirect() function in order to redirect it, but I am getting the following error in the console and the form does not submit

Mixed Content: The page at 'https://www.domain.com/form/' was loaded over HTTPS, but requested an insecure XMLHttpRequest endpoint 'http://www.domain.com/thankyou/'. This request has been blocked; the content must be served over HTTPS.

I have HTTPS set in my general > settings and I believe I have the htaccess file set up correctly as everything else on the site seems to work correctly. Is there a way I can troubleshoot this or get it to start working?

Thanks!

Try to avoid full URLs and instead use relative paths for things like images, JS, CSS

<img src="http://fulldomain/folder/file">    will cause alerts when viewed via https

<img src="./folder/file">  will not cause alerts